Tracking system using radio frequency signals
First Claim
1. A tracking system comprising:
- a) a satellite unit having;
i) first memory means for storing a unique identity code of the satellite unit;
ii) first receiving means for receiving a coded radio frequency search signal;
iii) first transmitting means for transmitting a coded radio frequency response signal, wherein the search signal includes a search identity code and a pseudo-random delay code, and wherein the response signal includes the unique identity code of the satellite unit;
iv) first control means connected to the first memory means, the first receiving means, and the first transmitting means for decoding the search signal, for determining whether the search identity code matches the unique identity code, for calculating a delay period from the delay code, and for controlling the first transmitting means such that the first transmitting means transmits the response signal at the end of the delay period only when the search identity code matches the unique identity code; and
b) a master unit having;
i) user controls for selecting the satellite unit to be located;
ii) second memory means for storing the unique identity code of the satellite unit and a series of numbers from which to select the delay code;
iii) second transmitting means for transmitting the search signal;
iv) second receiving means for receiving the response signal, wherein the second receiving means includes signal strength means for determining a strength of the response signal;
v) second control means connected to the user controls, the second memory means, the second transmitting means, and the second receiving means for selecting the delay code from the series of numbers and for controlling the second transmitting means such that when a user of the master unit selects the satellite unit to be located, the second transmitting means transmits the search signal with the selected delay code and with the search identity code matching the unique identity code of the satellite unit; and
vi) indicator means connected to the signal strength means for indicating to the user the strength of the response signal, wherein the second receiving means comprises a directional antenna oriented in the master unit such that the response signal received by the master unit is strongest when the master unit is pointed directly at the satellite unit.
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Accused Products
Abstract
A tracking system comprising multiple satellite units and a master unit for selectively and individually locating each satellite unit. Each satellite unit receives a search signal from the master unit and transmits a response signal to the master unit when the search signal contains a search identity code which matches a unique identity code of the satellite unit. The master unit has user controls for selecting any one of the satellite units to be located and a memory for storing the unique identity code of each satellite unit. The master unit also has an indicator circuit for indicating the strength of the response signal and a display and speaker for visually and audibly indicating the strength to a user. The master unit is programmed such that when the user selects one of satellite units to be located, the master unit transmits a search signal having a search identity code which matches the unique identity code of the selected satellite unit. The tracking system also preferably includes a passive re-radiating strip to be attached to an object to be tracked. The strip receives signals from the master unit at a fundamental frequency and re-radiates the signals at a multiple of the fundamental frequency. The master unit indicates the strength of the re-radiated signals to the user, enabling the user to locate the strip.
104 Citations
31 Claims
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1. A tracking system comprising:
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a) a satellite unit having; i) first memory means for storing a unique identity code of the satellite unit; ii) first receiving means for receiving a coded radio frequency search signal; iii) first transmitting means for transmitting a coded radio frequency response signal, wherein the search signal includes a search identity code and a pseudo-random delay code, and wherein the response signal includes the unique identity code of the satellite unit; iv) first control means connected to the first memory means, the first receiving means, and the first transmitting means for decoding the search signal, for determining whether the search identity code matches the unique identity code, for calculating a delay period from the delay code, and for controlling the first transmitting means such that the first transmitting means transmits the response signal at the end of the delay period only when the search identity code matches the unique identity code; and b) a master unit having; i) user controls for selecting the satellite unit to be located; ii) second memory means for storing the unique identity code of the satellite unit and a series of numbers from which to select the delay code; iii) second transmitting means for transmitting the search signal; iv) second receiving means for receiving the response signal, wherein the second receiving means includes signal strength means for determining a strength of the response signal; v) second control means connected to the user controls, the second memory means, the second transmitting means, and the second receiving means for selecting the delay code from the series of numbers and for controlling the second transmitting means such that when a user of the master unit selects the satellite unit to be located, the second transmitting means transmits the search signal with the selected delay code and with the search identity code matching the unique identity code of the satellite unit; and vi) indicator means connected to the signal strength means for indicating to the user the strength of the response signal, wherein the second receiving means comprises a directional antenna oriented in the master unit such that the response signal received by the master unit is strongest when the master unit is pointed directly at the satellite unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A tracking system comprising:
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a) a re-radiating strip for re-radiating a radio frequency search signal; and b) a master unit having a transmitting means for transmitting said search signal, a user control means for instructing said master unit to transmit said search signal, and a receiving means for receiving the re-radiated signal from said strip, said receiving means including a signal strength means for determining a strength of the re-radiated signal, said master unit also having a second control means connected to said user control means, said transmitting means, and said receiving means for controlling said transmitting means such that said transmitting means transmits said search signal when a user of said master unit activates said user control means, and said master unit further having an indicator means connected to said signal strength means for indicating to the user the strength of the re-radiated signal. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification